JP2023012208A - Semiconductor device - Google Patents

Abstract

To provide a semiconductor device capable of reducing a stress.SOLUTION: A semiconductor device 100 comprises a semiconductor element 1, a heat spreader 2 composed of a high thermal conductive material and joined to the semiconductor element 1, and a chiller 3 bonded to the heat spreader 2 on a surface facing a surface bonded to the semiconductor element 1 among surfaces of the heat spreader 2. Thermal conductivity of the heat spreader 2 is greater than thermal conductivity of the chiller 3. A groove 4 opening on a bonding surface between the heat spreader 2 and the chiller 3 is formed in the heat spreader 2. A shape of the bonding surface between the heat spreader 2 and the chiller 3 is rectangular. At least one of virtual extension lines 5 extending along a longitudinal direction of the groove 4 crosses a surface 8 on which a long side of the heat spreader 2 is formed.SELECTED DRAWING: Figure 1

Description

The present invention relates to semiconductor devices.

2. Description of the Related Art Conventionally, there has been known a heat dissipation device that relieves stress (thermal stress) caused by heat generated by a heating element (Patent Document 1). The heat mass member described in Patent Document 1 has a stress relief portion and a heat mass portion in its thickness direction.

Japanese Patent Application Laid-Open No. 2009-130060

However, in the heat dissipation device described in Patent Document 1, a sufficient stress relaxation effect cannot be obtained with the aspect ratio of the contact surface between the cooler and the heat mass member.

SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductor device capable of reducing stress.

A semiconductor device according to an aspect of the present invention includes a semiconductor element, a heat spreader that is made of a high thermal conductive material and is bonded to the semiconductor element, and a surface of the heat spreader that faces the surface that is bonded to the semiconductor element, a cooler coupled with the heat spreader. The heat spreader is formed with a groove that opens to the joint surface between the heat spreader and the cooler. At least one of imaginary extension lines extending along the longitudinal direction of the groove intersects the plane forming the long side of the heat spreader.

According to the present invention, stress can be reduced.

FIG. 1 is a top view of a semiconductor device 100 according to the first embodiment. FIG. 2 is a cross-sectional view taken along line AA of FIG. FIG. 3 is a top view of a semiconductor device 100 according to the second embodiment. FIG. 4 is a cross-sectional view of a semiconductor device 100 according to the third embodiment. FIG. 5 is a cross-sectional view of a semiconductor device 100 according to the fourth embodiment. FIG. 6 is a top view of the semiconductor device 100 according to the fifth embodiment. FIG. 7 is a top view of a semiconductor device 100 according to the sixth embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description of the drawings, the same parts are denoted by the same reference numerals, and the description thereof is omitted.

(First embodiment)
A semiconductor device 100 according to the first embodiment will be described with reference to FIGS. FIG. 1 is a top view of a semiconductor device 100. FIG. FIG. 2 is a cross-sectional view taken along line AA of FIG.

As shown in FIGS. 1 and 2, one surface of the semiconductor element 1 and one surface of the heat spreader 2 are bonded together. The surface of the semiconductor element 1 that is visible when the semiconductor device 100 is viewed from the top is referred to as the "upper surface," the surface opposite to the "upper surface" is the "lower surface," and the surface of the heat spreader 2 that is visible when the semiconductor device 100 is viewed from the top is the "upper surface." When the surface opposite to the "upper surface" is defined as the "lower surface", it is expressed that the lower surface of the semiconductor element 1 and the upper surface of the heat spreader 2 are joined together. A well-known method is used for joining. Well-known methods include, for example, soldering, metal bonding, diffusion bonding, and the like.

The semiconductor element 1 is not particularly limited, but is an IGBT (Insulated Gate Bipolar Transistor) as an example. The heat spreader 2 is used to improve heat radiation efficiency, and is made of a highly heat conductive material. An example of a high thermal conductivity material is copper.

The heat spreader 2 and the cooler 3 are bonded to each other on the surface facing the bonding surface between the semiconductor element 1 and the heat spreader 2 . When the surface of the cooler 3 visible in the top view of the semiconductor device 100 is defined as the "upper surface" and the surface opposite to the "upper surface" is defined as the "lower surface", the lower surface of the heat spreader 2 and the upper surface of the cooler 3 are joined. It is expressed as being The cooler 3 is made of aluminum as an example. Therefore, the thermal conductivity of the heat spreader 2 is higher than that of the cooler 3 in this embodiment. A plurality of plate-like fins 10 are provided in the cooler 3 , and gaps 11 are formed between the fins 10 . Reference numeral 6 in FIG. 1 indicates the longitudinal direction of the heat spreader 2 . Reference numeral 6 also indicates the longitudinal direction of the joint surface directions of the heat spreader 2 and the cooler 3 . The heat spreader 2 and the cooler 3 are joined such that the longitudinal direction of the heat spreader 2 and the longitudinal direction of the fins 10 are the same. In this embodiment, a multi-hole tube is used as the cooler 3, but an open-type cooler such as comb teeth may be used. The shapes of the semiconductor element 1, the heat spreader 2, and the cooler 3 are not particularly limited, but are rectangular as an example.

As shown in FIGS. 1 and 2, grooves 4 are formed in the heat spreader 2 . The groove 4 opens at the joint surface between the heat spreader 2 and the cooler 3 . Also, the joint surface between the heat spreader 2 and the cooler 3 has a rectangular shape. Reference numeral 9 indicates the longitudinal direction of groove 4 . Reference numeral 9 also indicates the lateral direction of the directions of the joint surfaces of the heat spreader 2 and the cooler 3 . A reference numeral 5 indicates an extension line of the groove 4 . More specifically, reference numeral 5 indicates an imaginary extension line extending along the longitudinal direction of groove 4 . Reference numeral 8 denotes a surface (side surface) forming the long side of the heat spreader 2 in a side view of the semiconductor device 100 . At least one of the extension lines 5 intersects the plane 8 forming the long side of the heat spreader 2 at the joint plane between the heat spreader 2 and the cooler 3 . A crossing point is indicated by the numeral 7 . The position of the plane where the extension line 5 intersects may be any position among the planes forming the long sides of the heat spreader 2 . Therefore, the extension line 5 may intersect the plane 8 forming the long side of the heat spreader 2 at a position other than the joining plane between the heat spreader 2 and the cooler 3 .

(Effect)
A semiconductor device 100 according to the first embodiment includes a semiconductor element 1, a heat spreader 2 made of a high thermal conductive material and bonded to the semiconductor element 1, and a surface of the heat spreader 2 bonded to the semiconductor element 1. a cooler 3 joined to the heat spreader 2 on opposite surfaces. The heat spreader 2 has a higher thermal conductivity than the cooler 3 . The heat spreader 2 is formed with a groove 4 that opens to the joint surface between the heat spreader 2 and the cooler 3 . The joint surface between the heat spreader 2 and the cooler 3 has a rectangular shape. At least one of imaginary extension lines 5 extending along the longitudinal direction of groove 4 intersects surface 8 forming the long side of heat spreader 2 . This makes it easier for the heat spreader 2 to expand and contract in the longitudinal direction 6, making it possible to reduce stress.

The cooler 3 also has a plurality of plate-like fins 10 formed in the same direction as the long sides of the heat spreader 2 . By forming the fins 10 in the same direction as the longitudinal direction 6 of the contact surface between the heat spreader 2 and the cooler 3 in this manner, the stress reduction effect is further enhanced.

1 and 2, the groove 4 is formed perpendicular to the joint surface between the heat spreader 2 and the cooler 3, but this is an example and does not have to be formed perpendicular.

(Second embodiment)
Next, a semiconductor device 100 according to a second embodiment will be described with reference to FIG. In the second embodiment, as shown in FIG. 3, the grooves 4 reach the ends (both ends) of the heat spreader 2 . In other words, the grooves 4 are open on the surfaces (both surfaces) forming the long sides of the heat spreader 2 . The groove 4 may be expressed as reaching the surfaces (both surfaces) forming the long sides of the heat spreader 2 . As a result, the heat spreader 2 is divided by the grooves 4, so that the effect of reducing the stress is further enhanced.

(Third Embodiment)
Next, a semiconductor device 100 according to a third embodiment will be described with reference to FIG. Reference numeral 13 in FIG. 4 indicates the groove bottom of the groove 4 , and reference numeral 14 indicates the opening of the groove 4 formed on the joint surface between the heat spreader 2 and the cooler 3 . Reference L1 in FIG. 4 indicates the length of the groove bottom 13 in the longitudinal direction 9, reference L2 indicates the length of one side of the semiconductor element 1 in cross section, and reference L3 indicates the length of the opening 14 in the longitudinal direction 9. indicates The relationship between the lengths L1 to L3 is L3>L2>L1. As shown in FIG. 4, the length L1 of the groove bottom 13 in the longitudinal direction 9 of the groove 4 is shorter than the length L3 of the opening 14 in the longitudinal direction 9 of the groove 4, and shorter than L2. It has been described that an example of the shape of the semiconductor element 1 is square. Length L1 is shorter than the length of any side (arbitrary side) of the four sides of semiconductor element 1 . By tapering the groove 4 (providing the groove bottom 13) in this manner, a heat path can be secured, and heat resistance can be reduced. In FIG. 4, a trapezoidal shape is explained as an example of the taper, but the taper may be formed in a triangular shape. In this case, instead of the groove bottom 13, a vertex is formed.

(Fourth embodiment)
Next, a semiconductor device 100 according to a fourth embodiment will be described with reference to FIG. Reference character L4 in FIG. 5 indicates the depth of the groove 4, and reference character L5 indicates the length from the groove bottom 13 to the joint surface between the semiconductor element 1 and the heat spreader 2. As shown in FIG. "The depth of the groove 4" is the length from the opening 14 to the groove bottom 13 in a cross-sectional view. The relationship between symbols L4 and L5 is L5>L4. The depth L4 of the groove 4 is shorter than the length L5 from the groove bottom 13 of the groove 4 to the joint surface between the semiconductor chip 1 and the heat spreader 2. As shown in FIG. That is, the groove bottom 13 and the bonding surface between the semiconductor element 1 and the heat spreader 2 are separated by a predetermined distance (length L5). Since the groove bottom 13 corresponds to the stress relaxation portion, the joint surface between the semiconductor element 1 and the heat spreader 2 is not in contact with the stress relaxation portion (the groove bottom 13). As a result, the thickness (length L5) for heat diffusion can be ensured, and the thermal resistance can be further reduced. The relationship between the symbols L4 to L5 is not particularly limited as long as L5>L4, but L4 may be set to be less than 50% of L5.

(Fifth embodiment)
Next, a semiconductor device 100 according to a fifth embodiment will be described with reference to FIG. In the fifth embodiment, as shown in FIG. 6, a plurality of grooves 4 are formed. In FIG. 6, three grooves 4 are formed. This makes it easier for the heat spreader 2 to expand and contract, making it possible to further reduce the stress. Although the grooves 4 are formed so as not to cross each other in FIG. 6, the grooves 4 may be formed so as to cross each other. 6, each groove 4 reaches the end of the heat spreader 2, but this is an example, and each groove 4 does not reach the end of the heat spreader 2 as shown in FIG. good.

(Sixth embodiment)
Next, a semiconductor device 100 according to a sixth embodiment will be described with reference to FIG. The sixth embodiment is the same as the fifth embodiment in that a plurality of grooves 4 are formed. In the sixth embodiment, as shown in FIG. 7, a plurality of semiconductor elements 1 to be bonded to the heat spreader 2 are also provided. In FIG. 7, two semiconductor elements 1 are provided. As shown in FIG. 7, when the plurality of semiconductor elements 1 and the plurality of grooves 4 are projected onto the joint surface between the heat spreader 2 and the cooler 3, the plurality of grooves 4 are formed so as to partition the plurality of semiconductor elements 1. be. At this time, it is preferable that the groove 4 is formed at the center (or near the center) of the heat spreader 2 . As shown in FIG. 7, a plurality of grooves 4 are formed so as to partition the semiconductor element 1, and one of the plurality of grooves 4 is formed at the center (or near the center) of the heat spreader 2. The effect of stress relaxation has a wide effect on the joint surface between the heat spreader 2 and the cooler 3, and it becomes possible to relax the thermal interference between the semiconductor elements 1. FIG. Although each groove 4 reaches the end of the heat spreader 2 in FIG. 7, this is an example, and each groove 4 does not reach the end of the heat spreader 2 as shown in FIG. good.

While embodiments of the present invention have been described above, the discussion and drawings forming part of this disclosure should not be construed as limiting the invention. Various alternative embodiments, implementations and operational techniques will become apparent to those skilled in the art from this disclosure.

REFERENCE SIGNS LIST 100 semiconductor device 1 semiconductor element 2 heat spreader 3 cooler 4 groove 10 fin 13 groove bottom 14 opening

Claims (7)

a semiconductor element;
a heat spreader made of a highly thermally conductive material and bonded to the semiconductor element;
a cooler bonded to the heat spreader on a surface of the heat spreader facing the surface bonded to the semiconductor element;
the thermal conductivity of the heat spreader is greater than the thermal conductivity of the cooler;
The heat spreader is formed with a groove that opens to a joint surface between the heat spreader and the cooler,
The joint surface between the heat spreader and the cooler has a rectangular shape,
A semiconductor device, wherein at least one of imaginary extension lines extending along the longitudinal direction of the groove intersects a plane forming a long side of the heat spreader. 2. The semiconductor device according to claim 1, wherein said cooler has a plurality of plate-like fins formed in the same direction as the long sides of said heat spreader. 3. The semiconductor device according to claim 1, wherein said groove is open to a surface forming a long side of said heat spreader. The length of the groove bottom in the longitudinal direction of the groove is shorter than the length of the opening in the longitudinal direction of the groove and shorter than the length of any side of the semiconductor element. The semiconductor device according to any one of items 1 and 2. 5. The semiconductor device according to claim 1, wherein a depth of said groove is shorter than a length from a groove bottom of said groove to a bonding surface between said semiconductor element and said heat spreader. 6. The semiconductor device according to claim 1, wherein a plurality of said grooves are formed. A plurality of the semiconductor elements bonded to the heat spreader are provided,
The plurality of grooves are formed so as to partition the plurality of semiconductor elements when the plurality of semiconductor elements and the plurality of grooves are projected onto the joint surface between the heat spreader and the cooler. 7. The semiconductor device according to claim 6.

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